Stainless steel pipe is a kind of hollow long round steel, which is mainly used in industrial transportation pipelines and mechanical structural components such as petroleum, chemical industry, medical treatment, food, light industry, mechanical instrument and so on. In addition, when the bending and torsional strength are the same, the weight is lighter, so it is also widely used in the manufacture of mechanical parts and engineering structures. It is also commonly used as furniture and kitchenware.

Hardness of stainless steel pipe

Stainless steel pipes are generally measured by three hardness indicators: Brinell, Rockwell and Vickers.

• Brinell hardness

Among the stainless steel pipe standards, Brinell hardness is the most widely used, and the hardness of the material is often expressed by the indentation diameter, which is both intuitive and convenient. However, it is not suitable for steel pipes of harder or thinner steel.

• Rockwell hardness

The Rockwell hardness test of stainless steel pipe is the same as the Brinell hardness test, which is an indentation test method. The difference is that it measures the depth of the indentation. Rockwell hardness test is a widely used method, among which HRC is second only to Brinell hardness HB in steel pipe standards. Rockwell hardness can be used to measure metal materials from extremely soft to extremely hard. It makes up for the inadequacy of the Brinell method. It is simpler than the Brinell method and can directly read the hardness value from the dial of the hardness machine. However, due to its small indentation, the hardness value is not as accurate as the Brinell method.

• Vickers hardness

Vickers hardness test of stainless steel pipe is also an indentation test method, which can be used to determine the hardness of very thin metal materials and surface layers. It has the main advantages of Brinell and Rockwell methods, and overcomes their basic shortcomings, but it is not as simple as the Rockwell method, and the Vickers method is rarely used in steel pipe standards.

Production method of stainless steel pipe

Stainless steel pipes are divided into two categories: seamless pipes and welded pipes according to production methods. Seamless steel pipes can be divided into hot-rolled pipes, cold-rolled pipes, cold-drawn pipes and extruded pipes. Cold-drawn and cold-rolled pipes are the secondary Processing; welded pipes are divided into straight seam welded pipes and spiral welded pipes.

Sectional shape of stainless steel pipe

Stainless steel pipes can be divided into round pipes and special-shaped pipes according to the cross-sectional shape. Special-shaped tubes include rectangular tubes, diamond-shaped tubes, elliptical tubes, hexagonal tubes, octagonal tubes and various asymmetrical tubes. Special-shaped tubes are widely used in various structural parts, tools and mechanical parts. Compared with the round tube, the special-shaped tube generally has a larger moment of inertia and section modulus, and has a larger resistance to bending and torsion, which can greatly reduce the weight of the structure and save steel.

Stainless steel pipes can be divided into equal-section pipes and variable-section pipes according to the shape of the longitudinal section. Variable section tubes include tapered tubes, stepped tubes and periodic section tubes.